A common design for circuit breaker motor operators utilizes a ratcheting mechanism for coupling the drive of an electromotive device, such as a motor, to the breaker operating mechanism pursuant to charging its contact closing springs. Examples of such circuit breaker motor operator ratcheting mechanisms can be seen in U.S. Pat. Nos. 3,097,275; 3,525,956; 3,585,330; 3,600,540; 3,652,815; 3,773,995; 3,806,684; and 3,944,772. Basically, these ratcheting mechanisms include a driving pawl coupled with the electromotive device for incrementally advancing a ratchet wheel coupled with the breaker operating mechanism. Each incremental advance of the ratchet wheel is sustained by a holding pawl. Ultimately, the ratchet wheel is advanced to an angular position where the closing springs are fully charged and therefore empowered to forcibly close the breaker contacts. Typically, the discharge of the closing springs rapidly drives the ratchet wheel in the same direction as did the driving pawl in charging the closing springs. In the process, the teeth on the ratchet wheel impact with the driving and holding pawls, producing undue pawl and ratchet wear, as well as unnecessary stress on the pawl springs and mountings. Moreover, when the breaker contacts close, there is an inevitable rebound which tends to rotate the ratchet wheel somewhat in the opposite direction. Under these circumstances, the straight sides of the ratchet teeth impact against the straight edges of the pawl tips, causing potentially damaging stresses in the ratcheting mechanism.
It is accordingly an object of the present invention to provide an improved ratcheting mechanism for circuit breaker motor operators.
A further object is to provide a circuit breaker motor operator which utilizes a ratcheting mechanism of improved construction and enhanced operating life.
Another object is to provide a motor operator of the above character wherein the ratcheting mechanism includes means for automatically detaining the ratcheting pawls in inoperative positions removed from the ratchet wheel while the ratchet wheel is being overdriven by the circuit breaker operating mechanism.
An additional object is to provide a circuit breaker motor operator ratcheting mechanism of the above character which is efficient in design, inexpensive to manufacture and reliable in operation.
Other objects of the invention will in part be obvious and in part appear hereinafter.